KR102175374B1 - Apparatus and method for half duplex wireless repeaters - Google Patents

Abstract

The present invention relates to a half-duplex wireless relay apparatus and method.
A half-duplex wireless relay apparatus according to the present invention includes: an antenna switching unit for setting a transmission path or a reception path for a plurality of antennas; A receiving circuit unit for receiving an analog signal transmitted from the antenna switching unit; An AD conversion unit converting the received analog signal into a digital signal; A signal detection unit detecting whether there is a signal to be relayed from the converted digital signal; And when a signal to be relayed by the signal detection unit is detected, a reception path is set for an arbitrary antenna receiving a signal among the plurality of antennas, and a transmission path is set for the remaining antennas not receiving signals among the plurality of antennas. So, it characterized in that it comprises a control unit for controlling the antenna switching unit.

Description

Apparatus and method for half duplex wireless repeaters}

The present invention relates to a half-duplex wireless relay apparatus and method, and more particularly, to a half-duplex wireless relay apparatus and method for relaying communication devices using a half-duplex wireless communication method, such as a radio.

A wireless relay device is an equipment used to eliminate a shadow area in an area where communication is required, and facilitates communication between a base station and a terminal (mobile station) or between a terminal and a terminal. In recent years, with the development of mobile communication, many relay devices have been developed and used to resolve shadow areas in the mobile communication service area, and the technology has also made remarkable developments.

On the other hand, the traditional wireless communication method, radio, is still used as an essential communication method in various industrial sites. Recently, the importance of the wireless communication auxiliary equipment has been strengthened due to the securing of the national disaster safety communication network and the reinforcement of fire safety standards. . However, the development and use of a relay device for a radio or broadcast service using a half-duplex communication method is relatively weak compared to mobile communication.

Conventional technologies related to the half-duplex wireless relay device include Korean Patent No. 10-1097406 (a wireless relay device and method for single-frequency short communication), and Korean Patent No. 10-1736244 (emergency disaster communication system).

These prior art are separately provided with a first signal processing unit (transmitting/receiving circuit unit) for transmitting signals from a first mobile station to a second mobile station and a second signal processing unit (transmitting/receiving circuit unit) for transmitting signals from the second mobile station to the first mobile station. , Turning on/off the first and second signal processing units (transmitting/receiving circuit units) of the wireless relay device by using the hook signals of the first and second mobile stations as synchronization signals.

However, in the prior art, a synchronization signal detection unit, a signal processing unit (transmitting/receiving circuit unit), and the like for the first path for transmitting signals from the first mobile station to the second mobile station and the second path for transmitting signals from the second mobile station to the first mobile station, respectively. Since it is equipped with, there is a problem of high complexity and low economic efficiency by implementing the same circuit redundantly.

In addition, the prior art implements a half-duplex wireless communication device and method in consideration of the form of using only two antennas. If there are several shaded areas (e.g., when three or more antennas are required), several wireless relays Since the devices (main donor and one or more sub-donors) must be interlocked, installation is difficult and expensive.

On the other hand, recently, digital radios capable of not only voice communication but also text communication or data communication have been commercialized.Since the conventional technology uses the hook signal of the mobile station as a synchronization signal, text communication or data communication cannot be used in the case of digital radios. There was a problem that voice communication could also be limited.

Korean Patent Publication No. 10-1097406 Korean Patent Publication No. 10-1736244

The present invention was devised to solve the above-described problems, and an object of the present invention is to be easily implemented with one wireless relay device without increasing the complexity of the circuit even when multiple antennas are used due to the large number of shaded areas. It is to provide a half-duplex wireless relay apparatus and method.

Another object of the present invention is to provide a half-duplex wireless relay apparatus and method for converting an analog signal received from an antenna into a digital signal and detecting whether there is a signal to be relayed for a digital signal.

Another object of the present invention is to provide a half-duplex wireless relay apparatus and method for converting an analog signal received from an antenna into a digital signal, selectively filtering the digital signal, and upscaling to a preset level.

Another object of the present invention is to provide a half-duplex wireless relay apparatus and method for converting an analog signal received from an antenna into a digital signal, delaying the digital signal for a preset delay time, and then transmitting it.

Another object of the present invention is to provide a half-duplex wireless relay apparatus and method that can be applied not only to analog radios that perform only voice communication but also digital radios that can also perform text communication or data communication.

For the above purposes, a half-duplex wireless relay apparatus according to an embodiment of the present invention includes: an antenna switching unit for setting a transmission path or a reception path for a plurality of antennas; A receiving circuit unit for receiving an analog signal transmitted from the antenna switching unit; An AD conversion unit converting the received analog signal into a digital signal; A signal detection unit detecting whether there is a signal to be relayed from the converted digital signal; And when a signal to be relayed by the signal detection unit is detected, a reception path is set for an arbitrary antenna receiving a signal among the plurality of antennas, and a transmission path is set for the remaining antennas not receiving signals among the plurality of antennas. So, it characterized in that it comprises a control unit for controlling the antenna switching unit.

In addition, a half-duplex wireless relay apparatus according to another aspect of the present invention includes: an antenna switching unit for setting a transmission path or a reception path for a plurality of antennas; A receiving circuit unit for receiving an analog signal transmitted from the antenna switching unit; An AD conversion unit converting the received analog signal into a digital signal; A channel selection unit filtering at least one pre-selected channel frequency for the converted digital signal; A signal detection unit detecting whether there is a signal to be relayed from the filtered digital signal; And when a signal to be relayed by the signal detection unit is detected, a reception path is set for an arbitrary antenna receiving a signal among the plurality of antennas, and a transmission path is set for the remaining antennas not receiving signals among the plurality of antennas. So, it characterized in that it comprises a control unit for controlling the antenna switching unit.

Preferably, the signal detection unit comprises: a size calculator for calculating a size of a digital signal; And a comparator for determining whether there is a signal to be relayed by comparing the signal amplitude calculated by the amplitude calculator with a preset threshold.

Alternatively, the signal detection unit may include a plurality of narrowband filters for filtering by dividing at least one preselected channel frequency band or a band including the same into a plurality of narrowbands; A plurality of size calculators each calculating a size of a signal filtered by the plurality of narrowband filters; A plurality of comparators for detecting whether there is a signal to be relayed for each narrow band by comparing the signal magnitudes calculated by the plurality of magnitude calculators with a preset threshold value; And a determiner that receives the detection results of the plurality of comparators and determines whether there is a signal to be relayed.

Meanwhile, a half-duplex wireless relay method according to an aspect of the present invention includes the steps of: receiving an analog signal through an arbitrary antenna among a plurality of antennas; Converting the received analog signal into a digital signal; Detecting whether there is a signal to be relayed from the converted digital signal; And when the signal to be relayed is detected, setting a reception path for an antenna that receives a signal among the plurality of antennas, and setting a transmission path for the remaining antennas that do not receive a signal among the plurality of antennas. Characterized in that.

In addition, a half-duplex wireless relay method according to another aspect of the present invention includes: receiving an analog signal through an arbitrary antenna among a plurality of antennas; Converting the received analog signal into a digital signal; Filtering at least one pre-selected channel frequency for the converted digital signal; Detecting whether there is a signal to be relayed from the filtered digital signal; And when the signal to be relayed is detected, setting a reception path for an antenna that receives a signal among the plurality of antennas, and setting a transmission path for the remaining antennas that do not receive a signal among the plurality of antennas. Characterized in that.

Preferably, the detecting may include calculating a magnitude of a digital signal; And comparing the calculated signal level with a preset threshold to determine whether there is a signal to be relayed.

Alternatively, the detecting may include filtering the digital signal by dividing the digital signal into at least one preselected channel frequency band or a band including the same into a plurality of narrow bands; Dividing into the plurality of narrow bands and calculating the size of each filtered signal; Detecting whether there is a signal to be relayed in each narrow band by comparing the calculated signal level with a preset threshold; And determining whether there is a signal to be relayed based on a result of detecting whether there is a signal to be relayed in each of the narrow bands.

According to the present invention, since the transmission/reception circuit is not provided for each path according to the antenna combination, but one common transmission/reception circuit is provided regardless of the number of antennas, the effect of implementing efficiently at low cost without increasing the complexity of the circuit is achieved. Have.

And, according to the present invention, since the antenna switching unit is connected to a plurality of antennas to set a transmission path or a reception path, respectively, even when multiple antennas are used due to a large number of shaded areas, a single wireless relay device can be easily implemented. Has an effect.

In addition, according to the present invention, since an analog signal received from an antenna is converted into a digital signal and it detects whether there is a signal to be relayed to the digital signal, a signal-to-noise ratio ( By increasing SNR), it has the effect of reducing the probability of false detection and increasing the probability of detection.

In addition, according to the present invention, since the analog signal received from the antenna is converted to a digital signal, the digital signal is selectively filtered and upscaled to a preset level, it is easy even when the frequency band of the channel to be relayed is dispersed. It can be filtered and also has the effect of improving the performance of the transmission circuit as well as the reception performance of the radio by expanding the dynamic range of the signal to be relayed.

In addition, according to the present invention, since the analog signal received from the antenna is converted into a digital signal and then transmitted after delaying the digital signal for a preset delay time, when correct transmission/reception paths are set for a plurality of antennas. It has the effect of preventing the loss of the signal to be relayed by delaying the transmission until. And, accordingly, it has an effect that can be applied to digital radios that perform text communication or data communication as well as analog radios that perform only voice communication.

1 is a block diagram of a half-duplex wireless relay apparatus according to a first embodiment of the present invention.
2 is a configuration diagram of an antenna switching unit according to an embodiment of the present invention.
3 is a configuration diagram of an antenna switching unit according to another embodiment of the present invention.
4 is a configuration diagram of a signal detector according to an embodiment of the present invention.
5 is a block diagram of a channel selection unit according to an embodiment of the present invention.
6 is a block diagram of a half-duplex wireless relay device according to a second embodiment of the present invention.
7 shows an ROC curve (Receiver Operating Characteristic Curve) according to a change in SNR.
8 is a configuration diagram of a signal detector according to another embodiment of the present invention.
9 is a schematic diagram illustrating a method of detecting a signal using a plurality of narrowband filters.
10 shows a receiver operating characteristic curve (ROC) according to a change in the number of narrow-band filters.
11 is a block diagram of a half-duplex wireless relay apparatus according to a third embodiment of the present invention.
12 is a configuration diagram of an antenna switching unit according to another embodiment of the present invention.
13 is a block diagram of a half-duplex wireless relay device according to a fourth embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments. For reference, detailed descriptions of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted in the following description.

The bandwidth per channel of a typical radio is about 5 kHz, 6.5 kHz, and 12.5 kHz, and these channels are set at a bandwidth of 10 MHz to 70 MHz (or more) at a bandwidth interval per channel. For example, according to the safety standards of domestic wireless communication auxiliary equipment, a frequency of 440 MHz to 450 MHz is used for half-duplex wireless communication, and a bandwidth of 12.5 kHz per channel is allocated for a frequency bandwidth of 10 MHz, so that a total of 800 channels can be used.

For these half-duplex wireless communication channels, the subject of use (e.g., government offices, companies, hospitals) is generally determined for each channel (frequency) according to business and use, and channels (frequency) approved for use at sites such as government offices, companies, and hospitals. Half-duplex wireless communication is performed by selecting one or more channels (frequency) from among them. Accordingly, radios that are actually used in each site are mainly manufactured so that only 5 to 30 limited channels (frequency) can be used, and as a result, half-duplex radio relay devices that relay these radios are in principle used in actual sites. It only needs to be implemented so that only a few channels (frequency) can be relayed.

However, in order to be applied and used in a variety of sites other than a specific site in which a channel to be used is designated, a half-duplex wireless repeater must be able to relay signals from radios for various purposes (ie, radios with different channels). Therefore, most half-duplex wireless repeaters including the prior art are implemented in a manner that passes the entire half-duplex wireless communication frequency band or the entire band supported by the radio for various purposes (for example, a 40MHz band of 420MHz to 460MHz). And, even though it is implemented by passing only some frequency bands (e.g., 10 MHz bands of 440 MHz to 450 MHz) including the channel to be relayed (frequency), it is not used between and/or adjacent to the channels to be relayed (frequency). Channels (frequency) were also included. As a result, the half-duplex wireless repeater according to the prior art could not lead to optimal performance, and it was difficult to implement high precision due to the limitation of the analog bandpass filter.

On the other hand, the half-duplex wireless relay device according to the prior art, as described above, for a first path for transmitting a signal from a first mobile station to a second mobile station and a second path for transmitting a signal from the second mobile station to the first mobile station. Each includes a synchronization signal detection unit, a signal processing unit (transmission/reception circuit unit), and the like. Accordingly, the same circuit is implemented redundantly in the first path and the second path, resulting in high complexity and low economic efficiency. And, since the half-duplex wireless repeater according to the prior art has only two antennas, when there are several shaded areas (for example, when three or more antennas are required), several wireless repeaters (main donor and one The above sub-donors) are interlocked. As a result, in the prior art, when there are several shaded areas, installation is difficult and costs are high.

Hereinafter, a half-duplex wireless relay apparatus and method according to the present invention will be described in detail with reference to FIGS. 1 to 13.

First, FIG. 1 is a block diagram of a half-duplex wireless relay device according to a first embodiment of the present invention.

Referring to FIG. 1, a half-duplex wireless repeater 100 according to a first embodiment of the present invention includes an antenna switching unit 110, a receiving circuit unit 120, an AD conversion unit 130, a signal detection unit 140, And a control unit 150, a channel selection unit 160, a DA conversion unit 180, a transmission circuit unit 190, and the like.

The antenna switching unit 110 is connected to a plurality of antennas 101 and 102, and when a signal is received through an antenna among a plurality of antennas, it transmits the signal to the receiving circuit unit 120 and undergoes filtering, amplification, etc. The signal output from the transmission circuit unit 190 is transmitted to the remaining antennas among the plurality of antennas. For example, the antenna switching unit 110 is composed of a switch, as shown in Figs. 2 and 3, and when a signal is received from the first antenna 101, it is transmitted to the receiving circuit unit 120 and the transmitting circuit unit The signal output from 190 is transmitted to the second antenna 102, and when a signal is received from the second antenna 102, it is transmitted to the receiving circuit unit 120, and the signal output from the transmitting circuit unit 190 is transmitted to the first It is transmitted to the antenna 101. For reference, although a form having two antennas 101 and 102 is illustrated in FIG. 1, a form having three or more antennas is of course possible.

The reception circuit unit 120 removes components unnecessary for AD (Analog to Digital) conversion of the signal transmitted from the antenna conversion unit 110 and amplifies the signal to a size suitable for AD conversion. For example, the receiving circuit unit 120 is composed of a band pass filter (BPF), a low noise amplifier (LNA), a variable gain amplifier (VGA), etc., and the antenna switching unit 110 For the analog signal transmitted from the radio, pass (filter) only the entire band supported by the radio for various purposes (e.g., 40 MHz band of 420 MHz to 460 MHz) or only part of the band (e.g., 10 MHz band of 440 MHz to 450 MHz) for AD conversion. Unnecessary components are removed and amplified to a size suitable for AD conversion. In addition, the receiving circuit unit 120 amplifies the filtered analog signal to an intermediate frequency (IF) or a baseband to an appropriate size for AD conversion, if necessary.

The AD conversion unit 130 converts an analog signal output from the reception circuit unit 130 into a digital signal. For example, the AD converter 130 is composed of a sampler, a quantizer, etc., and samples the analog signal transmitted from the receiving circuit unit 130 while maintaining the phase and amplitude as it is. It quantizes to generate a digital signal.

The signal detection unit 140 determines whether there is a signal (radio signal) to be relayed from the digital signal output from the AD conversion unit 130, and transmits the result (signal detection result) to the control unit 150. Specific functions and features of the signal detection unit 140 according to the present invention will be described in detail below.

The control unit 150 determines the presence or absence of a radio signal based on the signal detection result transmitted from the signal detection unit 140, and if there is a radio signal, the controller 150 sets a reception path for the antenna currently receiving the radio signal, and The antenna switching unit 110 is controlled to set a transmission path for the other antennas. For example, the control unit 150 controls the antenna switching unit 110 so that the plurality of antennas 101 and 102 are sequentially connected to the reception circuit unit 120 in a standby state, and the signal detection unit 140 detects a signal. If the radio signal is detected from the result, the current connection state of the antenna switching unit 110 is maintained as it is, so that the radio signal is continuously received through the antenna connected to the current receiving circuit unit 120 and transmitted through the remaining antenna (Fig. 2). Alternatively, the control unit 150 controls the antenna switching unit 110 so that all the antennas 101 and 102 are connected to the reception circuit unit 120 in the standby state, and then the radio is transmitted from the signal detection result of the signal detection unit 140. When signal detection is confirmed, the antenna switching unit 110 is controlled so that the plurality of antennas 101 and 102 are sequentially connected to the receiving circuit unit 120 to detect the antenna currently receiving the signal, and receive any antenna When detected, the connection state is maintained as it is, so that the radio signal is continuously received through the antenna connected to the current receiving circuit unit 120 and transmitted through the remaining antennas (see FIG. 3).

Meanwhile, the channel selection unit 160 filters at least one pre-selected channel frequency for the digital signal output from the AD conversion unit 130. Specific functions and features of the channel selection unit 160 according to the present invention will be described in detail below.

The DA conversion unit 180 converts the digital signal output from the channel selection unit 160 into an analog signal. For example, the DA conversion unit 180 is composed of a resistor, an operational amplifier, and the like, and generates an analog signal corresponding to a digital signal output from the channel selection unit 160.

The transmission circuit unit 190 amplifies power after removing unnecessary components from the analog signal output from the DA conversion unit 180 and transmits the amplified power to the antenna conversion unit 190. For example, the transmission circuit unit 190 is composed of a band-pass filter, a power amplifier, etc., and amplifies it into power that can be transmitted by the antenna after removing unnecessary components from the analog signal output from the DA conversion unit 180 Then, it is transmitted to the antenna switching unit 190. In addition, the transmission circuit unit 190, if the frequency is shifted in the reception circuit unit 120 or the output frequency of the DA converter 180 is different from the frequency to be transmitted, the frequency is shifted to the actual transmission frequency.

Hereinafter, a signal detector according to the present invention will be described in detail with reference to FIG. 4.

4 is a configuration diagram of a signal detector according to an embodiment of the present invention. The signal detection unit can be implemented in various forms, and FIG. 4 is composed of a magnitude calculator, a comparator, etc. to compare the size of an input signal sample with a threshold value and determine that a signal has been detected when it is higher than the threshold value. The signal detector is illustrated.

Referring to FIG. 4, the signal detection unit 140' according to an embodiment of the present invention includes a size calculator 144', a comparator 146', and the like.

The size calculator 144 ′ calculates the size of the digital signal output from the AD conversion unit 130. In addition, the comparator 146' compares the signal level calculated by the size calculator 144' with a preset threshold, and the result of signal detection (e.g., H(1) when a radio signal is detected, and the radio signal is not detected). In case L(0)) is transmitted to the controller 150.

In detail, when the input signal of the signal detection unit 140' is expressed as x(mT), x(mT) is a carrier wave (or an intermediate frequency in the case of a frequency shift in the receiving circuit unit) ω _C as shown in Equation 1 below. It becomes the sum of the demodulated signal component s(mT) and the noise component n(mT).

[Equation 1]

Since x(mT) is a real number modulated with a carrier wave or an intermediate frequency, complex demodulation is performed as shown in Equation 2 below to form a complex number consisting of a real part z _r (mT) and an imaginary part z _i (mT) in the baseband. It can be represented by z _c (mT).

[Equation 2]

z _c (mT) = z _r (mT) + jz _i (mT) = s _r (mT) + n _r (mT) + j{s _i (mT) + n _i (mT)}

Here, s _r (mT), s _i (mT), n _r (mT), and n _i (mT) are the real part of the signal component, the imaginary part of the signal component, and the real part of the noise component of the complex number z _c (mT), respectively. It represents the negative and the imaginary part of the noise component.

Meanwhile, the signal power P _S and the noise power P _N are represented by Equations 3 and 4 below, respectively.

[Equation 3]

P _S = s _r ² (mT) + s _i ² (mT)

[Equation 4]

P _N = E{n _r ² (mT) + n _i ² (mT)}

Here, E{} means an expectation value. As is well known, the real and imaginary parts of the thermal noise are mutually independent, and are random variables having a complex Gaussian distribution with a variance of P _N and a mean of 0.

The size calculator 144 ′ calculates the size Λ of the signal input to the signal detector 140 ′, which may be calculated as shown in Equation 5 below.

[Equation 5]

Here, the thermal noise power P _N may be used as a measured value, but the bandwidth of the channel selection unit 160, the noise figure (NF) of the receiving circuit unit 120, and the input of the receiving circuit unit 120 to the AD conversion unit 130 It can also be calculated using the amplification degree and the conversion factor of the AD conversion unit 130.

The comparator 146' is a threshold value determined according to the preset probability of false alarm P _FA and the probability of detection P _D of the magnitude of the input signal calculated by the magnitude calculator 144'. It compares with (threshold) η to determine the presence or absence of a radio signal, and transmits the result (signal detection result) to the control unit 150.

Specifically, when H ₁ is a hypothesis that determines that there is a signal, H ₀ is a hypothesis that determines that there is no signal, and the threshold is η, the hypothesis test can be expressed as Equation 6 below. .

[Equation 6]

Here, test statistics Λ is a random variable having a Rician distribution. And, the cumulative distribution function (CDF) of Λ is given in Equation 7 below.

[Equation 7]

CDF _Λ = 1-Q ₁ (ν,Λ)

Here, ν = (P _S /P _N ) ^1/2 = SNR ^1/2 , and Q ₁ (ν,Λ) is a Marcum-Q function.

And, Probability of False Alarm P _FA Is obtained from the complementary cumulative distribution function (CCDF) of _Λ , i.e. 1-CDF _Λ when ν = 0, and the probability of detection P _D is by using the CCDF of Λ when ν = SNR ^1/2 You can get it.

Hereinafter, a channel selection unit according to the present invention will be described in detail with reference to FIG. 5.

5 is a block diagram of a channel selection unit according to an embodiment of the present invention.

Referring to FIG. 5, the channel selection unit 160 according to an embodiment of the present invention includes a digital filter 162 and a scaler 164.

The digital filter 162 selects and filters only a pre-selected channel frequency (eg, a channel frequency actually used in the field) for the digital signal output from the AD conversion unit 130. Further, the scaler 164 up-scales the digital signal filtered by the digital filter 162 to a preset level.

In detail, when it is assumed that two signals of r ₁ (t) and r ₂ (t) having different channel frequencies are input from the receiving circuit unit 120 in phase, the AD conversion unit 130 samples them in a time period of T. The maximum size of the (sampling) and AD-converted signal |x ₀ (mT)|max is the AD converter output component |r ₁ (mT) of r ₁ (t) as shown in Equation 8 below, since the AD converter has a linear characteristic. )|max and the output component of the AD converter of r ₂ (t) |r ₂ (mT)|max.

[Equation 8]

|x ₀ (mT)|max = |r ₁ (mT)|max + |r ₂ (mT)|max

If the channel of the selection unit 160 to only relay r ₁ (t) component, the digital filter 162 is passed through a ₁ r (mT) and mainly components r ₂ (mT) component is suppressed. The digital filter 162 can adjust the amplification of the passband signal and the suppression of signals other than the passband. By suppressing r ₂ (mT), the maximum size is Δ(Δ << |r ₂ (mT)|max ), the output x ₁ (mT) of the digital filter 162 becomes as in Equation 9 below.

[Equation 9]

|x ₁ (mT)|max = |r ₁ (mT)|max + Δ <|x ₀ (mT)|max

는 k를 넘지 않는 최대 정수를 의미한다.As a result, the maximum size of the output signal of the digital filter 162 is smaller than that of the input signal. For example, the maximum amplitude of r ₁ (t) is 0.5 Vp (Vp is the peak value), the maximum amplitude of r ₂ (t) is 0.5 Vp, and the maximum input range of the 16-bit AD converter is -1.0 V to 1.0 V. The conversion factor (that is, the conversion result value when converting 1.0V input to AD) is 2 ¹⁵ -1, the input range of the 16bit DA converter is -2 ¹⁵ ~ 2 ¹⁵ -1, and the output range accordingly is -1.0V ~ When the suppression degree for r ₂ (mT) is 1.0 V and 40 dB (0.01 times), the maximum values of the input and output of the digital filter 162 are as shown in Equations 10 and 11, respectively. For reference, in Equations 10 and 11 below

Means the maximum integer not exceeding k.

[Equation 10]

[Equation 11]

In addition, the scaler 164 up-scales the output of the digital filter 162 to a preset level. For example, in the case of a 16-bit DA converter with an input range of -2 ¹⁵ to 2 ¹⁵ -1 as described above, the scaler 164 converts |x ₁ (mT)|max (=16547) to |x ₀ (mT)|max The dynamic range of the digital signal transmitted to the DA conversion unit 180 is expanded by upscaling 1.9802 times to the (=2 ¹⁵ -1) level.

)까지 출력할 수 있다. 이러한 동적영역이 확대되는 이점은 DA 변환부(180)의 출력을 처리하는 송신 회로부(190)로부터 무전기의 수신부에 이르기까지 영향을 미쳐 성능을 향상시킨다.Therefore, when channel selection is not performed, the r ₁ (t) component can be output only 0.5 Vp due to the limitation of the dynamic range of the DA converter, but in the present invention, the output of the signal to be relayed by using the channel selection unit 160 is 1.9802. By upscaling the r ₁ (t) component to 0.9901V (

) Can be printed. The advantage of expanding the dynamic range affects the range from the transmission circuit unit 190 processing the output of the DA conversion unit 180 to the reception unit of the radio, thereby improving performance.

In addition, the signal passing through the channel selection unit 160 according to the present invention also improves the signal-to-noise ratio (SNR) to improve signal quality, which will be briefly described.

The signal-to-noise ratio (SNR) for thermal noise is as shown in Equation 12 below when the power of the signal to be relayed is P _S and the thermal noise power is P _N.

[Equation 12]

SNR = P _S /P _N

Since the power of the thermal noise component is proportional to the bandwidth, if the thermal noise power density is N ₀ , the bandwidth of the receiving circuit unit 120 is B _R , and the output noise density of the receiving circuit unit 120 is P _NR , then P _NR is Equation 13 below. Same as

[Equation 13]

P _NR = B _R ×N ₀

When the channel selection unit 160 selects a channel and passes only a signal within a bandwidth B _S (B _S <B _R ) narrower than the receiving circuit unit 120, the noise power P _NS of the channel selected signal is as shown in Equation 14 below.

[Equation 14]

P _NS = B _S ×N ₀ <P _NR

Therefore, if the signal-to-noise ratio before channel selection is SNR _R and the signal-to-noise ratio after channel selection is SNR _S , the relationship between SNR _R and SNR _S is as Equation 15 below.

[Equation 15]

SNR _R = P _S /P _NR <SNR _S = P _S /P _NS

Consequently, the signal-to-noise ratio is improved by B _R /B _S in inverse proportion to the bandwidth before and after channel selection. For example, when the output of the reception circuit unit 120 having a bandwidth of 40 MHz and an SNR of 0 dB is input to the channel selection unit 160, the total bandwidth of the output of the channel selection unit 160 is 20 MHz, 10 MHz, 5 MHz, and 2.5 MHz, respectively. In this case, the SNR of the output of the channel selector 160 is improved to 3dB, 6dB, 9dB, and 12dB, respectively. Further, the improvement of the signal-to-noise ratio not only improves the quality of the signal, but also improves the detection performance of the signal detection unit, as described below.

6 is a block diagram of a half-duplex wireless relay device according to a second embodiment of the present invention.

6, the half-duplex wireless repeater 200 according to the second embodiment of the present invention includes an antenna switching unit 210, a receiving circuit unit 220, an AD conversion unit 230, a signal detection unit 240, and It includes a control unit 250, a channel selection unit 260, a DA conversion unit 280, a transmission circuit unit 290, and the like.

The half-duplex wireless repeater 200 according to the second embodiment of the present invention shows a difference in the digital signal input to the signal detection unit compared to the half-duplex wireless repeater 100 according to the first embodiment described above, and the remaining components are Substantially the same or similar. Therefore, in the following description, the features and differences of the second embodiment compared to the first embodiment will be mainly described, and the remaining contents may be referred to the first embodiment.

In the second embodiment of the present invention, the signal detection unit 240 determines whether there is a signal (radio signal) to be relayed from the digital signal output from the channel selection unit 260, and calculates the result (signal detection result). It is transmitted to the control unit 250.

As described in the first embodiment, the channel selector 260 selects and filters only a channel frequency to be actually relayed for the digital signal output from the AD converter 230, and upscales the digital signal to a preset level. Accordingly, the radio signal passing through the channel selection unit 260 has a larger dynamic region than before passing through, and a signal-to-noise ratio is improved, thereby improving signal quality.

Therefore, when the signal detection unit 240 determines whether there is a signal (radio signal) to be relayed from the digital signal output from the channel selection unit 260, when detecting from the digital signal output from the AD conversion unit 230 More detection performance is improved.

As described above, when the output of the reception circuit unit 220 having a bandwidth of 40 MHz and an SNR of 0 dB is input to the channel selection unit 260, the total bandwidth of the output of the channel selection unit 260 is 20 MHz, 10 MHz, 5 MHz, respectively, In the case of 2.5MHz, the SNR of the output of the channel selector 260 is improved to 3dB, 6dB, 9dB, and 12dB, respectively. In this case, the signal detection unit according to an embodiment of the present invention (the signal detection unit 140' of the first embodiment) ), the false detection probability (P _FA ) and the detection probability (P _D ) in ROC curve (Receiver Operating Characteristic Curve) are shown in FIG. 7.

On the other hand, Figure 8 shows a signal detection unit 240" using a plurality of narrowband filters in another embodiment of the signal detection unit according to the present invention. And, Fig. 9 shows a plurality of signal detection units 240". It shows a method of detecting a signal using a narrowband filter.

8 and 9, the signal detector 240" includes a plurality of (N) narrowband filters 242"-1 to 242"-N, and a plurality of size calculators 244"-1 to 244. "-N), a plurality of comparators 246"-1 to 246"-N, a determiner 248", and the like.

The bandwidth B _R of the reception circuit unit 220 is, for example, 40 MHz (refer to FIG. 9A), and the channels to be relayed are distributed in a bandwidth of, for example, 10 MHz (B _S = B _S1 + B _S2 ), so that the channel selection unit 260 is 10 MHz ( When the relay bandwidth of 3MHz + 7MHz is selected (see FIG. 9B), the signal detection unit 240" divides it into N narrowband filters 242"-1 to 242"-N and filters it (FIG. 9C). Reference) Narrowband filters (242"-1 to 242"-N) are filters whose pass bandwidth is narrower than that of the input signal, and the bandwidth is preferably implemented as an integer multiple of the channel frequency interval of the radio. It is not limited.

N outputs that have passed through each narrow-band filter (242"-1 to 242"-N) are input to each size calculator (244"-1 to 244"-N) to calculate their size, and calculate each size The outputs of the groups 244"-1 to 244"-N are input to the comparators 246"-1 to 246"-N, respectively, and are compared with a preset threshold. And, the result (detection result) of each comparator 246"-1 to 246"-N is input to the determiner 248", and the determiner 248" includes N comparators 246"-1 to 246 If it is determined that any one of the detection results of "-N) has a signal, it is determined that the signal has been detected (see Fig. 9D).

When a signal is input to one channel within the relay bandwidth and the signal power has a signal-to-noise ratio of 0dB compared to thermal noise at the output of the receiving circuit unit 220, the bandwidth of the receiving circuit unit 220 (e.g., B _R = 40 MHz) It has already been described that the SNR increases by 4 times (6dB) by passing through the channel selector 260 having a 1/4 bandwidth (eg B _S = 10MHz). In the signal detection unit 240", since the channel bandwidth selected by the channel selection unit 260 is reduced to 1/N in each of the narrow-band filters 242"-1 to 242"-N, each narrow-band filter 242" -1 ~ 242"-N) The SNR of the output signal increases by N times, resulting in ν = [1/{10/(40×N)}] ^1/2 = 2×N ^1/2 .

When a radio signal is received, it passes through one narrow-band filter, so if ν = 2×N ^1/2 is substituted in Equation 7 above and the detection probability P _D of the signal is obtained from CCDF _Λ, that is, 1-CDF _Λ , then Equation 16 Same as

[Equation 16]

P _D = 1- CDF _Λ = 1-Q ₁ (2×N ^1/2 ,Λ)

On the other hand, when there is no signal, it is falsely detected unless all of the N narrow-band filters determine that there is no signal, and each of the N narrow-band filters passes only different signal bands, so they are mutually independent and since there is no signal, ν is 0. , Substituting ν = 0 in Equation 7 above and multiplying the value N times to find the probability of determining that there is no signal in all N narrowband filters when there is no signal, and then subtracting the value from the total probability 1 when there is no signal The false detection probability P _FA for determining that there is a signal is obtained by Equation 17 below.

[Equation 17]

P _FA = 1- CDF _Λ ^N = 1- {1- Q ₁ (0,Λ)} ^N

Accordingly, when N is 1, 2, 4, 8, and 16, the detection probability P _D and the false detection probability P _FA are expressed as ROC curves as shown in FIG. 10. In FIG. 10, in the case of N = 1, it is the same as a state in which the signal detector 240 does not have a narrow-band filter in a state in which the channel selector 260 passes only 10 MHz, so among the ROC curves for the SNR shown in FIG. It is the same as in the case of SNR = 6dB (for reference, in FIG. 10, the range of the horizontal axis (P _FA ) is expanded than in FIG. In addition, as the number of narrowband filters used in the signal detection unit 240" increases, such as N = 2, 4, 8, 16, as the bandwidth of each filter decreases, the detection performance is greatly improved.

For reference, the signal detection unit using a plurality of narrowband filters may also be applied to the first embodiment of the present invention. In this case, the signal detection unit 140 includes a plurality of narrowband filters for the output signals of the AD conversion unit 130. To detect the signal. In this case, the signal detection unit 140 may use a plurality of narrowband filters for the entire output signal bandwidth (eg, B _R = 40MHz) of the AD conversion unit 130, but the bandwidth of the channel to be relayed (eg, B _S = 10MHz) is preferably implemented using a plurality of narrowband filters. In addition, when a signal is detected in a channel that has passed through an arbitrary narrow-band filter among a plurality of narrow-band filters, the signal detection unit 140 passes the channel that has passed the corresponding narrow-band filter or a partial band including the channel. In order to control the selection unit 160, for example, it may be implemented to automatically set the selection channel of the channel selection unit 160.

11 is a block diagram of a half-duplex wireless relay apparatus according to a third embodiment of the present invention.

Referring to FIG. 11, the half-duplex wireless repeater 300 according to the third embodiment of the present invention includes an antenna switching unit 310, a first receiving circuit unit 321, a second receiving circuit unit 322, and a first AD conversion. A unit 331, a second AD conversion unit 332, a signal selection unit 340a, a signal detection unit 340, a control unit 350, a channel selection unit 360, a signal delay unit 370, a DA conversion unit 380, a transmission circuit unit 390, and the like.

In the half-duplex wireless relay device 300 according to the third embodiment of the present invention, compared to the half-duplex wireless relay device 100 according to the first embodiment, a receiving circuit unit and an AD conversion unit are provided for each path, and a signal selection unit and a signal It shows a difference in that a delay part is added, and the remaining configurations are substantially the same or similar. Therefore, in the following description, the features and differences of the third embodiment compared to the first embodiment will be mainly described, and the remaining contents may be referred to the first embodiment.

In the third embodiment of the present invention, the first receiving circuit unit 321 and the first AD conversion unit 331 remove components unnecessary for AD conversion with respect to the signal of the first path transmitted from the antenna switching unit 310, and After amplification to a size suitable for AD conversion, it is converted to AD. Similarly, the second reception circuit unit 322 and the second AD conversion unit 332 remove components unnecessary for AD conversion from the signal of the second path transmitted from the antenna conversion unit 310 and amplify the signal to a size suitable for AD conversion. Then convert to AD. According to a preferred embodiment of the present invention, the antenna switching unit 310 is implemented as shown in FIG. 12, for example, so that the signal of the first path is a sum of signals received through the first antenna 301 and the second antenna 302. Is set, and the signal of the second path is set to the signal received through the second antenna 302.

In addition, the signal selection unit 340a selects one of the signal of the first path transmitted from the first AD converter 331 and the signal of the second path transmitted from the second AD converter 332 Send to 340. For example, in the standby state, the signal selection unit 340a converts the signal of the first path transmitted from the first AD conversion unit 331 (that is, the sum of signals received through the first and second antennas) to the signal detection unit ( 340). And, if the signal detection unit 340 detects the radio signal and the signal detection unit 340 or the control unit 350 notifies the signal detection to the signal selection unit 340a, the signal selection unit 340a is the second AD The signal of the second path transmitted from the conversion unit 332 (ie, a signal received through the second antenna) is transmitted to the signal detection unit 340.

Then, the signal detection unit 340 determines whether there is a radio signal from the signal of the second path, and transmits the result (signal detection result) to the control unit 350. In addition, if the radio signal is detected from the signal of the second path, the control unit 350 sets a reception path for the second antenna 302 (ie, connects to the first reception circuit unit), and the first antenna 301 ), a transmission path is set (i.e., connected to the transmission circuit), and if a radio signal is not detected in the signal of the second path, a reception path is set for the first antenna 301 (i.e., the first reception A circuit unit) and a transmission path for the second antenna 302 is set (that is, connected to the transmission circuit unit).

Meanwhile, the signal delay unit 370 is provided between the channel selection unit 360 and the DA conversion unit 380 to delay the digital signal output from the channel selection unit 360 for a preset delay time, and then the DA conversion unit ( 380). For example, the signal delay unit 370 temporarily stores a digital signal (digital data) transmitted from the channel selection unit 360 by a memory or the like for a preset delay time and then transfers it to the DA conversion unit 380. In this case, the delay time in the signal delay unit 370 is determined by the control unit 350 by detecting the radio signal after the output signal of the first AD conversion unit 331 is input to the signal selection unit 340a. It is preferable that it is set to a time obtained by subtracting the processing time of the channel selection unit 360 from the time required until the state of 310) is controlled. Therefore, if the processing time of the channel processing unit 360 is sufficiently long, the signal delay unit 370 may be omitted.

For reference, in the embodiment of FIG. 11 described above, the first path and the second receiving circuit unit 322 and the second AD conversion unit 332 implemented by the first receiving circuit unit 321 and the first AD conversion unit 331 ), and the signal of the first path transmitted to the first receiving circuit unit 321 is set as the sum of signals received through the first antenna 301 and the second antenna 302, and , The signal of the second path transmitted to the second receiving circuit unit 322 is set as a signal received through the second antenna 302. However, alternatively, the output of the first receiving circuit unit 321 is connected to the input of the first AD conversion unit 331 and the output of the second receiving circuit unit 322 is connected to the first AD conversion unit 331 and the second After connecting to the input of the AD conversion unit 332, the signal transmitted to the first receiving circuit unit 321 is set as a signal received through the first antenna 301, and the signal transmitted to the second receiving circuit unit 322 May be set as a signal received through the second antenna 302.

13 is a block diagram of a half-duplex wireless relay device according to a fourth embodiment of the present invention.

13, a half-duplex wireless repeater 400 according to a fourth embodiment of the present invention includes an antenna switching unit 410, a first receiving circuit unit 421, a second receiving circuit unit 422, and an AD conversion unit ( 430, a band selection unit 440b, a signal detection unit 440, a control unit 450, a channel selection unit 460, a signal delay unit 470, a DA conversion unit 480, a transmission circuit unit 490, etc. Include.

In the half-duplex wireless relay device 400 according to the fourth embodiment of the present invention, a receiving circuit unit is provided for each path, and a band selector and a signal delay unit are added as compared with the half-duplex wireless relay device 100 according to the first embodiment. There is a difference in that, and the rest of the configurations are substantially the same or similar. In addition, compared with the half-duplex wireless relay device 300 according to the third embodiment described above, the difference is shown in that an AD conversion unit is implemented as one and a band selector is provided instead of a signal selection unit, and the remaining configurations are substantially the same or similar. . Therefore, in the following description, the features and differences of the fourth embodiment compared to the first and third embodiments will be mainly described, and the first and third embodiments may be referred to for the rest.

In the fourth embodiment of the present invention, the first receiving circuit unit 421 removes components unnecessary for AD conversion with respect to the signal of the first path transmitted from the antenna switching unit 410, modulates the signal into a first modulated signal, Amplify to a size suitable for transformation. Similarly, the second receiving circuit unit 422 removes components unnecessary for AD conversion from the signal of the second path transmitted from the antenna switching unit 410, and a second modulated signal (the frequency is different from the first modulated signal) And then amplified to a size suitable for AD conversion. According to a preferred embodiment of the present invention, the antenna switching unit 410 is implemented as shown in FIG. 12 described above, so that the signal of the first path is the signal received through the first antenna 401 and the second antenna 402. It is set to the sum, and the signal of the second path is set to the signal received through the second antenna 402.

In addition, the signal of the first path and the signal of the second path modulated at different frequencies in the first and second reception circuit units 421 and 422 are combined and input to the AD conversion unit 430, and the AD conversion unit 430 converts it into a digital signal. For reference, the signal of the first path and the signal of the second path input to the AD converter 430 are signals separated from each other on the frequency axis.

The band selector 440b selects a passband for the digital signal output from the AD conversion unit 430, filters it, and transmits it to the signal detector 340. For example, in the standby state, the band selector 440b selects and filters a band through which the signal of the first path (that is, the sum of signals received through the first and second antennas) may pass, and then the signal detector ( 440). And, if the signal detection unit 440 detects the radio signal and the signal detection unit 440 or the control unit 450 notifies the signal detection to the band selection unit 440b, the band selection unit 440b performs a second path A band through which only a signal of (that is, a signal received through the second antenna) is selected, filtered, and then transmitted to the signal detector 440.

Then, the signal detection unit 440 determines whether there is a radio signal from the signal of the second path and transmits the result (signal detection result) to the control unit 450. In addition, if the radio signal is detected from the signal of the second path, the control unit 450 sets a reception path for the second antenna 402 (ie, connects to the first reception circuit unit), and the first antenna 401 ), a transmission path is set (that is, connected to the transmission circuit unit), and if a radio signal is not detected in the signal of the second path, a reception path is set for the first antenna 401 (ie, the first reception Connection with the circuit unit) and a transmission path for the second antenna 402 (ie, connection with the transmission circuit unit).

Meanwhile, the signal delay unit 470 is provided between the channel selection unit 460 and the DA conversion unit 480 to delay the digital signal output from the channel selection unit 460 for a preset delay time, and then the DA conversion unit ( 480). For example, the signal delay unit 470 temporarily stores a digital signal (digital data) transmitted from the channel selection unit 460, which is composed of a memory or the like, for a preset delay time, and then transmits the digital signal to the DA conversion unit 480. In this case, the delay time of the signal delay unit 470 is determined by the control unit 450 by the radio signal detection after the output signal of the AD conversion unit 430 is input to the band selection unit 440b. It is preferable that it is set to a time obtained by subtracting the processing time of the channel selection unit 460 from the time required to control the state of. Accordingly, if the processing time of the channel processing unit 460 is sufficiently long, the signal delay unit 470 may be omitted.

For reference, in the case of the third and fourth embodiments having a signal delay unit, since the transmission is delayed until the correct transmission/reception path is established for a plurality of antennas, it is possible to relay without information and/or waveforms lost from the received signal. It is especially useful for digital radios that transmit information in block units.

Although the present invention has been described in detail with reference to preferred embodiments so far, those skilled in the art to which the present invention pertains can be implemented in various other specific forms without changing the technical spirit or essential features of the present invention. The embodiments are illustrative in all respects and should be understood as non-limiting.

And, the scope of the present invention is specified by the claims to be described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention. Should be interpreted as.

Claims (13)

delete As a half-duplex wireless relay device,
An antenna switching unit for setting a transmission path or a reception path for each of the plurality of antennas;
A receiving circuit unit for receiving an analog signal transmitted from the antenna switching unit;
An AD conversion unit converting the received analog signal into a digital signal;
A signal detection unit detecting whether there is a signal to be relayed from the converted digital signal; And
When the signal to be relayed is detected by the signal detection unit, a reception path is set for an arbitrary antenna receiving a signal among the plurality of antennas, and a transmission path is set for the remaining antennas that do not receive a signal among the plurality of antennas. And a control unit for controlling the antenna switching unit,
The receiving circuit unit includes a first receiving circuit unit for receiving an analog signal of a first path transmitted from the antenna switching unit and a second receiving circuit unit for receiving an analog signal of a second path transmitted from the antenna switching unit,
The AD conversion unit converts the analog signal of the first path output from the first receiving circuit unit into a digital signal and converts the analog signal of the second path output from the second receiving circuit unit into a digital signal Including a second AD conversion unit,
The half-duplex wireless relay device,
And a signal selection unit for selecting one of a digital signal of a first path output from the first AD conversion unit and a digital signal of a second path output from the second AD conversion unit and transmitting the selection to the signal detection unit. Half-duplex wireless repeater. As a half-duplex wireless relay device,
An antenna switching unit for setting a transmission path or a reception path for each of the plurality of antennas;
A receiving circuit unit for receiving an analog signal transmitted from the antenna switching unit;
An AD conversion unit converting the received analog signal into a digital signal;
A signal detection unit detecting whether there is a signal to be relayed from the converted digital signal; And
When the signal to be relayed is detected by the signal detection unit, a reception path is set for an arbitrary antenna receiving a signal among the plurality of antennas, and a transmission path is set for the remaining antennas that do not receive a signal among the plurality of antennas. And a control unit for controlling the antenna switching unit,
The receiving circuit unit receives the analog signal of the first path transmitted from the antenna switching unit and modulates the signal into a first modulated signal, and the second receiving circuit unit receives the analog signal of the second path transmitted from the antenna switching unit. Including a second receiving circuit for modulating the modulated signal,
The AD converter is a signal in which the analog signal of the first path modulated with the first modulated signal output from the first receiving circuit unit and the analog signal of the second path modulated with the second modulated signal output from the second receiving circuit unit are combined Receive and convert it to a digital signal,
The half-duplex wireless relay device,
A half-duplex wireless repeater further comprising a band selector for selectively filtering one of a digital signal of a first path or a digital signal of a second path from the digital signal output from the AD conversion unit and transmitting it to the signal detection unit. . The method according to claim 2 or 3,
And a channel selection unit that filters at least one pre-selected channel frequency for the converted digital signal. The method of claim 4,
The channel selection unit,
A digital filter for filtering at least one pre-selected channel frequency for the converted digital signal; And
And a scaler for up-scaling the filtered digital signal to a preset level. The method according to claim 2 or 3,
The signal detection unit,
A size calculator for calculating the size of the digital signal; And
And a comparator for determining whether or not there is a signal to be relayed by comparing the signal magnitude calculated by the magnitude calculator with a preset threshold. The method according to claim 2 or 3,
The signal detection unit,
A plurality of narrowband filters for filtering by dividing at least one preselected channel frequency band or a band including the same into a plurality of narrowbands;
A plurality of size calculators each calculating a size of a signal filtered by the plurality of narrowband filters;
A plurality of comparators for detecting whether there is a signal to be relayed for each narrow band by comparing the signal magnitudes calculated by the plurality of magnitude calculators with a preset threshold value; And
And a determiner for receiving detection results of the plurality of comparators and determining whether there is a signal to be relayed. The method according to claim 2 or 3,
The control unit sets a reception path for all of the plurality of antennas in a standby state, and when detecting that a signal is received through the arbitrary antenna, sets a transmission path for the remaining antennas not receiving the signal. Half-duplex wireless repeater. The method according to claim 2 or 3,
A channel selection unit filtering at least one pre-selected channel frequency for the converted digital signal; And
And a signal delay unit for delaying the digital signal output from the channel selection unit for a preset delay time. As a half-duplex wireless relay method,
Receiving an analog signal through any of a plurality of antennas;
Converting the received analog signal into a digital signal;
Detecting whether there is a signal to be relayed from the converted digital signal; And
When the signal to be relayed is detected, setting a reception path for an arbitrary antenna that receives a signal among the plurality of antennas, and setting a transmission path for the remaining antennas that do not receive a signal among the plurality of antennas, ,
The receiving step includes receiving a first analog signal through a first antenna and receiving a second analog signal through a second antenna,
The converting step includes converting the first analog signal into a first digital signal and converting the second analog signal into a second digital signal,
And the detecting step includes selecting one of the first digital signal and the second digital signal to detect whether there is a signal to be relayed. As a half-duplex wireless relay method,
Receiving an analog signal through any of a plurality of antennas;
Converting the received analog signal into a digital signal;
Detecting whether there is a signal to be relayed from the converted digital signal; And
When the signal to be relayed is detected, setting a reception path for an arbitrary antenna that receives a signal among the plurality of antennas, and setting a transmission path for the remaining antennas that do not receive a signal among the plurality of antennas, ,
The receiving step includes a process of receiving a first analog signal through a first antenna, modulating it into a first modulated signal, receiving a second analog signal through a second antenna, and modulating it into a second modulated signal,
The converting includes converting a signal obtained by combining the first analog signal modulated with the first modulated signal and the second analog signal modulated with the second modulated signal into a digital signal,
The detecting may include selectively filtering one of a digital signal corresponding to the first analog signal and a digital signal corresponding to the second analog signal from the digital signal; And detecting whether there is a signal to be relayed for the selectively filtered digital signal. The method of claim 10,
The detecting step,
Calculating the size of the digital signal; And
And determining whether there is a signal to be relayed by comparing the calculated signal level with a preset threshold. The method of claim 10,
The detecting step,
Dividing the digital signal into a plurality of narrow bands and filtering at least one preselected channel frequency band or a band including the same;
Dividing into the plurality of narrow bands and calculating the size of each filtered signal;
Detecting whether there is a signal to be relayed in each narrow band by comparing the calculated signal level with a preset threshold; And
And determining whether there is a signal to be relayed based on a result of detecting whether there is a signal to be relayed in each of the narrow bands.

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